Field of the Invention
The present invention relates to a stepless speed changer capable of reducing its size and reducing the cost by lessening the number of parts composing the device and shortening the length in the axial direction.
Description of the Related Art
One of the known stepless speed changers has a structure to change the speed by changing the contact point between a pair of discs.
This speed changer is, as schematically shown in FIG. 3, composed of a friction disc (a) on the output side and a rotary disc (b) on the input side which rotates by inclining at a small angle with regard to the center line of rotation of the friction disc (a), and a torque from the input side is transmitted to the output side by pressing the friction disc (a) against the rotary disc (b), and at the same time, the contact point is deflected by moving the rotary disc (b) while maintaining the pressing state, thereby changing the speed.
The friction disc (a) rotates, as stated above, coaxially with the output shaft (c) while being pushed toward the rotary disc (b).
In order to push the friction disc (a), a cam (d) leading to move along the shaft core of the output shaft (c) and a spring (e) thrusting the friction disc (a) toward the rotary disc (b) are provided.
It was therefore necessary to install the cam (d) coaxially with the output shaft (c), and as shown in FIG. 4 conventionally, a cylindrical cam shaft (f) having the cam (d) was mounted on the outside of the output shaft (c), and by a bearing (i) in the cam shaft (f), the output shaft (c) was axially supported, the cam shaft (f) itself was axially supported on a case (g), and the cam shaft (f) and the friction disc (a) were fixed.
Accordingly, for the purpose of axially supporting the cam shaft (f) preceisely and coaxially with the shaft core of the output shaft (c), a plurality of bearings (h) were arranged laterally in the space against the case (g), so that the cam shaft (f) was long, which caused a problem that the dimension of the speed changer in the axial direction became long.
The present invention endeavors to shorten the cam shaft (f), and as a result by firmly supporting pivotally the cam shaft (f) and the output shaft (c), which had been axially supported at one point and let stand purposelessly, the cam shaft (f) could be easily supported axially on the case (g).